Thermionic tube construction



1 J. J. GL-AUBER I V THERMIONIC TUBE CONSTRUCTION m Tm a Na 1 u v ma. a J W N Y 1 I I I I B H/ W J 7 5 2 W 6 5 5 ii f ,0 M a ATTORNEYS Patented Nov. 22, 1938 UNITED STATES PATENT OFFICE THERMIONIG TUBE CONSTRUCTION Application July 8, 1935, Serial No. 30,342

3 Claims.

This invention relates to electron discharge devices, and more particularly to new and improved means for securing the electrode assembly of such devices in a firm and properly positioned relationship with reference to the enclosing envelope of the wall of the device.

In present day manufacture of electron discharge devices of the type generally known as radio tubes consisting of an electrode assembly positioned within an envelope, it is of increasing importance that means be provided to prevent vibration due to external shock either against the envelope itself or against the supports of the envelope. Use of radio tubes, for example, on automobiles and other vehicles, and subjection of the apparatus to continued vibration from external sources require development of apparatus to overcome the accompanying ill effects of vibration upon the electrical action and efficiency of the tube.

In my co-pending application Serial No. 693,281, filed October 12, 1933, entitled Tube element shock absorber, now Patent No. 2,089,647, I have described a satisfactory and eflicient means for absorbing such vibration consisting of an E-shaped strip of mica formed from a rectangular plate having edge extensions on one side forming tongues, the tongues being adapted to engage the electrode assembly and the ends of the mica strip to engage, under tension, theinner wall of the tube. The central tongue of this device engages a member of the electrode assembly in such a manner as .to resist separation or detachment therefrom.

It is an object of the invention of this application to provide improved means for attaching the strip of the shock absorber device or spacer to the electrode assembly of an electron discharge tube or device. An additional object of the invention is to provide an attaching means between the shock absorber mica strip and the electrode assembly which does not require material modification of the electrode assembly cooperating member. Still another object of the s invention is to provide an attachment means between the resilient yielding shock absorbing element and the electrode assembly of a radio tube which is essentially firm and secure and will not become detached after insertion within the dome-shaped head of the radio tube. A further object is to provide a type of locking means between the mica strip and electrode assembly which is distributed along the length of the strip and not concentrated at one particular point, and in this manner lessening the strain at One point of the strip. An object, also, is to provide a type of locking means which will not require unnecessary removal of material from the body of the strip, thereby causing a weakening of its structure. The invention is described specifically in the claims hereto appended, but in order to set forth the form of the invention which may be preferred and the process of making the same, reference is made to the following detailed description of an embodiment of the invention and to the accompanying drawing, in which:

Fig. 1 is an elevation in section of a radio tube to which my invention is applied;

Fig. 2 is a sectional view taken along the lines 2-2 of Fig. 1;

Fig. 3 is another section taken along the lines 3-3 of Fig. 1;

Fig. 4 is an elevation in section at 90 to the line of viewpoint of Fig. 1 with parts removed; and

Fig. 5 is a perspective View of the shock absorber device employed in the present invention.

In the drawing I have shown a type of radio tube having an envelope H), which may be of glass or other substance not permeable to gases, which is mounted on a base H of insulation material, cup-shape in form, from the under side of which project the various contact terminals l2, to which the various electrodes Within the tube are connected. Within the envelope reentrant stem I3 is fused at its top about the base of the anode rods l4 and IS, the support rods I 6 and H, the grid support rods l8, and the oathode heater lead-in posts l9.

As will be seen from inspection of Fig. 1 of the drawing, the electrode assembly, generally designated by the numeral 28, consists of a series of concentric electrodes mounted upon and connected to the various standards M to I9 inclusive. At the center in the axis of the assembly is the cathode 2| formed of nickel externally coated with electron emitting materials such as the alkaline earth metal oxides and within which is the heating filament 22 formed of a coil of coated insulation wire electrically connected to the lead-in posts l9. Surrounding the cathode 2| is the control grid 23 which is a wire coil of narrow cylindrical formation surrounding the cathode throughout its length. Additional grids are designated by the numerals 24 and 25 and consist of coils of wire surrounding each other, the coil 25 being external tothe coil 24, and the coil 24 being external .to the coil 23. Enclosing t e Cathode and grids above mentioned is the plate or anode cylinder 26 which consists of solid metal sheeting. As shown, the method of attaching the support rods l4 and l5 to the anode is by means of the formation of an axial groove along the external surface of the anode in which the standard rods lie and are-welded.

Surrounding the anode is the screen mesh cylinder 9, which consists of a closely perforated metal webbing or mesh, which in turn is supported by means of a wire connection 2'! to the top of the stem.

The various grids above mentioned, namely 23, 24 and 25, are supported in position with reference to the cathode and anode by means of a plurality of support rods 28, each grid having two of these rods spaced equally from the axis of the tube, and about which the grid is wound. The axis of the various support rods 28, as well as the cathode and the anode support rods IS and II, are sufiiciently elongated to extend above and below the electrode assembly and pass through the rectangular insulation strips 29 at the top and at the lower end of the electrode assembly,

apertures being provided in the insulation mate rial for this purpose. These strips 29, which may be of mica, are each positioned respectively with in a dish-shaped metal cap 38 and 3| against which the mica strips 29 are held by the action of the various coiled wire grids.

As clearly shown in section in Fig. 1, the top cap 30 is a dish-shaped member having a central recess or depression forming a circular flat base 33, and an annular radial flat rim 34, the rim terminating in an annular ring of cylindrical formation with an outwardly flared flange 36. The base 33 of the top end cap 30 is formed with a diametric slot 31, the side edges 38 of which are bent back to form shielding members, and the end edges 39 of which are bent upwardly to form contact members with the supporting rods I6 and I1. Depressions 40 are also formed in the base 33 which extend toward the mica insulation plates 29 and serve to space the same from the metal surface of the cap. In the radial portion 34 of the cap 38 rectangular apertures 4| approximately parallel to the tangent of the cap are cut at spaced intervals about the periphery in order to receive the cooperating member of the insulating spacer units as will be hereinafter described.

The lower ends of the various support rods 28 are adapted to be inserted in the lower insulation strip 29, as hereinabove mentioned. This strip rests in the lower cap 3| which consists of a circular flat metal plate having an upwardly extending annular flange about its edge. The plate is slotted diametrically as at 42 in the area where the mica plate 29 rests with the ends of the support rods extending through the insulation plate and slot to points beneath the plate, where connection is made to the various lead-in wires or electrical connections mounted on the stem |3. The edges of the metal along the lower slot 42 are turned downwardly to form protecting shields 43 for the ends of the support rods, and the material at the end of the slot 42 is also turned up against the support rods that connect to the standards l6 and I1 and welded thereto 50 as to maintain the cap 3| in position in the assembly.

In both end strips 29 central apertures are formed to receive the ends of the cathode 2| which protrude beyond the limits of the end caps. The grid 23 has external connection by means of the connecting wire 44 and the contact 45 at the top of the tube. Attention is directed to the fact that the envelope I0 is of the so-called dome type, that is, the top of the tube or the end opposite the base is dome-shaped with a cylindrical portion 46, this construction having a practical use in connection with the shock absorbing device, as will hereinafter be described.

The shock absorber device or spacer is shown in perspective in Fig. 5 of the drawing and consists of a unit 50 having a whole strip 5| provided with three tongues or projections on a side edge two of these tongues 52 and 53 being at the ends of the strip 5|, and the third 54 being intermediate the ends. These tongues are separated by open areas 55 and 56, and the tongues 52 and 53 on their inner sides opposite the open areas 55 and 58 are each provided with notches 51 and 58 respectively which serve as the means for locking the shock absorbing unit in engagement with the electrode structure. The material of the shock absorber is mica, preferably, since it is insulating and heat resisting and has a relatively low heat conductivity. It is also electrically non-conducting and hence may be employed in connection with metal contacts either in the electrode unit or in the envelope without the necessity of adding insulating supports. It is, of course, obvious that other materials may be substituted for the mica, which may be even conducting provided the ends of the contacting areas of the shock absorber be properly electrically and heat insulated. A requirement of this shock absorbing unit is that it should be resilient so that the ends may flex in relation to the midpoint of the unit.

The shock absorber unit 58 is utilized in connection with the electrode assembly by inserting the tongue 54 of the unit into the slot 4| in the top cap 30 of the assembly unit. The outer tongues 52 and 53 with the insertion of the tongue 54 in the slot 4|, are positioned externally to the outer ring 35 of the cap 30 and bear against this flange on their inner edges. When the spacer 50 is forced completely into position with the strip 5| in contact with the metal of the cap the notches 51 and 58 on the inner sides of the tongues 52 and 53 ride over and engage the outerly extending projecting flange 36 of the ring 35 and consequently the member 50 is thereby held in engagement thereby. When the required number of shock absorber units 58 have been positioned in the slots 4|, three being indicated, although more or less may be usable, the electrode unit as a whole is inserted within the envelope and when the shock absorbing unit comes in contact with the dome-shaped top of the envelope, the ends of the spacers are pressed inwardly and yield to permit insertion of the assembly so that the upper'end thereof is within the space of the dome-shaped cavity. In such position the various spacers are flexed or bowed resiliently against the dome wall 48 with the two ends thereof in contact with said wall and with the notches 51 and 58 permanently fixed in engagement with the projecting flange 36 of the ring 35 of the top cap. Due to the retention of the central tongue 54 in the slot 4| it is apparent that by this connection the central portion of the mica member is reinforced when subjected to the flexing operation. It is also apparent that due to the flexibility of the material used the member 50 is able to accommodate itself to the variations in curvature or distortions in the surface of the envelope. In such assemblies as where the top of the mica member 50 contacts with the curved top of a dome it is evident that the mica may flex along its vertical axis to accommodate itself to this change in curvature also.

As shown the spacer 50 is attached fixedly to the top cap 30 by notches formed in the end tongues. Obviously, however, the member 50 may be held in position by a single notch connection formed in any one of the tongues or two notches in the central tongue cooperatively engaging the edge of the slots 4|, the essential feature being an interengagement between a notch on one member and a projecting edge on the other brought about by a flexing of the spacer.

Various other modifications of the invention may be made other than those here shown, the invention being limited only by the terminology of the claims hereto appended.

What I claim is:

1. An electron discharge device comprising an envelope having a tubular portion, an electrode assembly positioned within said envelope, a support member attached to said electrode assembly having a radially extending flange lying within said tubular portion of the envelope, and a spacer element comprising a strip of resilient material provided with tongues extending from one edge thereof said tongues engaging the flange, and one of said tongues having a notch on the edge thereof adapted to engage cooperatively the flange of the support member whereby the spacer is held in position between the support and the tubular portion of the envelope.

2. An electron discharge device comprising an envelope having a tubular portion, an electrode assembly positioned within said envelope, a support member comprising a flattened metal plate provided with a radial edge flange, and spaced, tangentially formed slots adjacent the flange, said plate being attached to the electrode assembly within the tubular portion of the envelope, and a spacer element comprising a strip of resilient material provided with tongues extending from one edge thereof, one of said tongues being positioned in one of the tangential slots, and another of said tongues having a notched edge adapted to engage cooperatively the flange on the support member.

3. An electron discharge device comprising an envelope having a tubular portion, an electrode assembly positioned within said envelope, a support member attached tosaid electrode assembly having a radially extending and circular rim having slots formed therein, a cylindrical ring on the edge of said rim, and a radially extending flange on the edge of said ring, said rim, ring and flange lying within the tubular portion of the envelope, and a spacer element comprising a strip of resilient material provided with three tongues extending from one edge thereof, two of said tongues having notches adapted to engage said flange and the other of said tongues engaging said slot, said ring being interposed between said slot and the tongues engaging the flange.

JOHN J. GLAUBER. 

